1. Field of the Invention
This invention relates to a vaccine for parainfluenza virus and to a method for producing the vaccine. More particularly, it relates to an attenuated, live parainfluenza virus for human administration to protect against infection, and to the method for preparing the attenuated virus strain.
Parainfluenza viruses, members of the myxovirus family, were discovered in 1952. These viruses are a major cause of respiratory infections, especially in children, where life-threatening upper and lower respiratory tract infections occur. The clinical spectrum includes pharyngitis, bronchitis, croup, and bronchopneumonia. It has been reported that parainfluenza virus types 1, 2 and 3 are associated with approximately a third of the cases of acute laryngotracheobronchitis and 8 to 17 percent of the cases of bronchopneumonia in infants and children. In adults, these viral agents occasionally cause upper respiratory tract infection and uncommonly, pneumonia.
2. Objects of the Invention
It is, accordingly, an object of the present invention to provide a safe, effective parainfluenza virus. Another object is to provide a parainfluenza virus which is antigenic while nonpathogenic. A further object is to provide a parainfluenza vaccine which protects against the effects of this virus on both initial and subsequent challenge. Still another object is to provide physiologically acceptable compositions for administering parainfluenza vaccine. Yet another object is to provide a method for attenuating parainfluenza virus. Another object is to provide a method for preparing a parainfluenza virus vaccine. These and other objects of the present invention will be apparent from the following description.